And the series on what is muscular failure continues. In the weight room part 2, I looked the issue of the Repetition Maximum (RM), defined as the maximum number of repetitions completed prior to reaching failure during a set. In the strictest sense this means that RM should always be one repetition less than the number of reps that resulted in muscular failure. If you failed, or would have failed, on repetition 13, then that is a 12RM.
That led into actual definitions of muscular failure. I started with the strictest physiological definition which is the point at which muscular force output falls below muscular force requirements (noting again that this is not synonymous with exhaustion). Once again I present my lovingly drawn image.
But, as always, in the weight room this is more complicated. Because now we have exercise form to be considered. I mean, yes, we could define failure as the most repetitions performed no matter what the trainee does.
Bouncing a bar off your chest, heave-hoing a barbell curl? Just accept it all, right? Except that this is unlikely to get a trainee any closer to muscular failure in the strictest sense since the reps being accomplished probably aren’t working the target muscle.
This led into the concept of form failure, performing the maximal number of repetitions possible until form starts to deviate from the goal or some definition of proper. I discussed a ton of issues here including how we would even operationally define this. That is, at what point has form deviated “enough” for the set to be stopped.
I also brought up the issue that form failure on on a technical complex compound movement on a squat, bench or (god forbid) deadlift is likely to put a trainee much further away from physiological muscular failure than a leg press or leg extension (where there isn’t really any form to break).
To this I made the point that, in both a research and a real-world sense, the reality is that all but the most advanced trainees don’t have the technical stability to get anywhere close to true muscular failure on a squat or bench before form breaks.
And don’t tell me that college students with 2-4 years of experience can do it, moreso on high reps and moreso on a short rest interval. Because 25 years in the weight room observing trainees on my part tells me it’s bullshit. Want to prove me wrong? Send me a video. I’ve only been waiting 18 months for someone to do so.
Don’t misunderstand what I’m saying here. I’m not saying that using form failure as an endpoint for a set is invalid. What I’m saying is that, depending on the exercise involved and the skill level of the trainee, using form failure may put them far far away from actual physiological muscular failure in the target muscle. And inasmuch as stressing the target muscle (or the single muscle being measured in a study) is a key to drawing meaningful conclusions….this definition may have problems.
I brought up a bunch of other issues related to this in a research sense, read the piece if you’re coming in late.
But with that out of the day, I want to push through and address some other definitions of failure along with potential issues that come up in actually defining or even “reaching” failure for the average trainee.
Let me note that throughout today’s article, I will be using a number of quotes from a a presentation titled Critical Commentary on the Stimulus for Muscle Hypertrophy in Experienced Trainees by Ralph Carpinelli. To say that he has been critical of much of the research and recommendations of resistance training is a bit of an understatement. But rather than link the paper multiple times, I’ll just mention his name.
As one of the many terms that you will see thrown around is the idea of volitional muscular failure. In a 2017 review titled Training to Fatigue: The Answer for Standardization When Assessing Muscle Hypertrophy? Dankel et al. state:
With respect to resistance exercise, there is a need for a more standardized protocol aimed at reducing individual variability by prescribing exercise to volitional fatigue as this will result in a common stimulus applied to all individuals.
But while the phrase “volitional fatigue” is used throughout the paper, it is never operationally defined. However, it would be most commonly taken to mean that the trainee continues a set until they decide or choose that they have reached a point of fatigue. Hence they choose by their own volition to terminate the set.
This goes back to the idea of the self-determined RM I mentioned in the previous part of this series. Basically, trainees are allowed to decide when they have reached their RM and would achieve failure on the next repetition.
Within each workout and its volume, the subjects performed a minimum of 8-12 SELF-DETERMINED MAXIMUM REPETITIONS at 75% of max. If individuals couldn’t get to the bottom of the rep range, they were given 30 seconds of rest within the set to do so. So if they got 6 reps, they got to rest for 30 seconds and get two more.
And well, that’s crap.
As Carpinelli puts it
Contrary to those definitions, the term volitional fatigue implies a conscious, deliberate, voluntary decision to terminate a set. However, individuals possess relatively different tolerances of psychological/physiological discomfort and consequently variable inter-individual perceptions of volitional fatigue.
Because recall from the last part that the definition of RM (and by extension failure as RM+1) is that a maximal effort has been given. And this gets us into a really big issue in terms of training in general, defining failure, how this interacts with the form issue, etc.
The Ability to Push in Training
And the issue that the above brings up is the actual ability to push in training. By that I mean the ability to push through discomfort and to provide a truly maximal effort.
Now if you have a really good memory you might recall the statement I made all the way back in the first part of this series which was:
When the subject is no longer able to generate as much force as needed, muscular task failure will occur. And please pay attention to that phrasing carefully.
Because what I said was when the “subject is no longer able to generate as much force” NOT “when the muscle is no longer able to generate as much force.” And there is a difference of some relevance to this topic although I won’t get into that until the next article.
The basic distinction I’m making here is between actual physiological muscular force failure and the trainee essentially giving up. Now, someone could make a fairly credible argument that you can’t separate the two. Recall my schematic of how muscles generate force:
And my mention that fatigue can at any of about 7 steps from the brain to the muscle. Well in the strictest sense, a trainee simply giving up or deciding they had had enough would be one of those steps. If you simply decide to stop pushing, your muscles will no longer generate sufficient force.
Giving Up vs. Hitting Failure
But that doesn’t mean that you have hit true physiological force failure in terms of what the actual skeletal muscle is doing or has experienced. If you’re leg pressing with a 20RM weight but at 15 it hurts so much that you decide you’ve hit failure and stop the set, you have not subjected the muscles to actual physiological task failure. And it is that physiological task failure that is relevant in terms of muscle growth.
Researchers can actually examine this, and frequently do with EMS. This is usually done to try to separate out central (brain/nervous system) and peripheral (everything past the neuromuscular junction out). So if someone hits fatigue and they apply EMS and the muscle generates more force, then fatigue was central. If it doesn’t, the muscle was truly fatigued.
Because the reality is that, in certain exercises anyhow, the average trainee is more likely to simply give up and decide they have hit failure than actually hit failure. Yes, yes, I know, we’ve got RIR and RTF as tools for this. I’ll come back to this in the final part.
But even there, to know what RIR/RTF you’re at means knowing that true failure (by which I mean actual failure when you have given a maximal effort) is. And as I’ll show with videos next time, most of you factually do not. And you can’t use a tool like RIR/RTF when you don’t have the appropriate anchor point (which is true muscular failure).
Perception of Effort vs. Discomfort
Research has looked this quite a bit. The paper Clarity in Reporting Terminology of Set End Points in Resistance Training by Steele et al. I cited in the previous part has a long discussion of this.
Some key quotes:
In our definitions we have anchored intensity of effort as being maximal at the point of MF [muscular failure]. This is partly due to the reasoning given above regarding differentiation of fatigue and failure. However, we believe this is also necessary due to the apparent difficulty people experience in differentiating between perceptions of effort and discomfort.
A number of studies [34-38] measuring rating of perceived exertion (RPE) using a Borg CR10 scale  (where a value of 10 indicates maximal effort) have reported that participants exercised to MF and received verbal encouragement to ensure adequate motivation and effort. In this case, each trial, irrespective of exercise, load, or training status should have resulted in a maximal value for effort, since people were exercising to MF.
Though those studies which have compared training to MF with training not to MF show that RPE for the active muscle is indeed higher when training to MF [37,38], maximal values (e.g. a score of 10) were not reported in any of the studies cited. Thus we can only assume that the participants were unclear as to how to report their perception of effort.
They mention that higher perceptions of effort occur with lower body training, higher volumes and increased work rate (I take this to mean shorter rest intervals but could be wrong about that). Face it, sets of 10 in the squat hurt more than sets of 10 in the barbell curl. Which do you think the average person is going to take closer to true muscular failure? Which do you think they are more likely to stop when it gets too uncomfortable to finish?
In this vein Shimano et al. measured RPE in the bench press, curl and squat at 60%, 80% and 90% of 1RM. While bench and curl showed no difference, reported RPE was higher in the squat at 60% vs. 80% and 90%. And I think the reason is clear: the higher reps in a full body exercise like a squat at 60% hurt far more than at 80% or 90%. Yes, a triple at 90% is hard but it’s a different “kind” of hard than doing high reps.
Compared to the bench press or curl, higher rep squats are systematically fatiguing. Anybody who has done the 20 rep squat routine, I mean truly done it, knows what I’m talking about. Past about rep 12 or so, all you want to do is to stop. Or die. Usually die.
Related: Is There a Best Way to Squat?
And the key to the routine is pushing past the discomfort, grinding out the next rep. And the next rep and the next rep. Pausing, breathing like a freight train as every neuron in your body tells you to stop.
Here’s a good demonstration, Jesse Marunde (R.I.P.) doing 407X20 in the squat and then collapsing on the floor. The set starts at 1:17 or you can jump to 2:47 to see the last 5 reps.
And the reality is that most people will simply stop. And they will stop, depending on a bunch of different variables, when it gets to a level of discomfort they are no longer willing to tolerate. And depending on them, their background, their training experience, etc. that may be very far away indeed from actual muscular failure.
Finally Steele et al. state
If persons are inappropriately anchoring their perceptions of effort upon feelings of discomfort, they may be likely to end their sets further from the point of MF [muscular failure] than expected if they were using RM or self-determined RM as a set end point.
Though I’d argue that self-determined RM has the same fundamental problem: you are letting someone decide, usually based on their fatigue or discomfort that they can’t do any more reps.
And, simply, they are usually wrong. When they get a happy sadist like myself to talk them through a set, they find out just how much more they had in the tank than they thought.
Learning to Push
The ability to push through discomfort to true failure is a learned skill. And, once again, having watched people for 25 years in the weight room, the number I’ve seen who can do it I can count on a couple of hands. Who can push and push through increasing levels of true discomfort to get even close or true muscular failure I can probably count on a few hands. And I trained most of them myself.
An old training partner of mine was inhuman in this regard. I once watched him squat something like 315X17, rack the bar, take his belt off and then get back under the bar to get the last 3. I watched him squat until he’d collapse on the floor in the rack. Then he’d look at me and say “Leg extensions.”
Track cyclist Sir Chris Hoy was supposed to be inhuman in his ability to push. He’d do bike intervals until he collapsed and vomited. He once attempted an altitude world record in the 1000m (which he missed by a soul crushing 0.005 seconds) that put him in shock.
And I think you’ll find that most top athletes have that ability.
And everybody else….does not. Most people stop when it gets challenging. It’s simply the fact. I’m not saying it’s everyone. I am saying it’s the majority I’ve ever watched over 25 years in commercial gyms. People stop when it gets more challenging than they are willing to tolerate. And depending on the person that can be far far from actual physiological muscular task failure.
My point ultimately being that I don’t really believe that the average trainee in most hypertrophy studies is giving anywhere close to that level of effort. And that’s moreso the case on a complex movement like a squat or bench press. And even moreso on a short rest interval. That’s on top of the form issue with technique rapidly deteriorating under those conditions.
Which means that all of those supposed “sets to failure” (form or otherwise) aren’t going to be anywhere close to physiological muscular failure. The average trainee is giving up when it gets more difficult/uncomfortable than they are willing to tolerate.
As always: Send me a video if you want to prove me wrong.
Ok, we’re almost there.
Repetition Speed Failure
In at least some research, especially recently, it has become common to control repetition speed during the exercise. I don’t mean just studies where repetition speed is being compared but rather general studies. It’s just part of the attempt to standardize the training and minimize variables.
For example, in the original volume study by Schoenfeld et al. it is stated:
The cadence of repetitions was carried out in a controlled fashion, with a concentric action of approximately 1 second and an eccentric action of approximately 2 seconds.
And this seems to be more and more common. And while not as common, failure has been occasionally defined relative to repetition speed.
In a paper titled Evidence-Based Resistance Training Recommendations Fisher et al. state:
Based on this, we can perhaps define “momentary muscular failure” as the inability to perform any more concentric contractions, without significant change to posture or repetition duration, against a given resistance.
I’m going to take “change to posture” as synonymous with form failure but it’s the second part I want to focus on. Because basically they are saying that if the goal repetition speed is a 2 second concentric and the trainee moved more slowly than that that should be defined as reaching failure.
Similarly, more addressing the idea of comparing specific repetition speeds within a given study, Carpinelli states:
This may consequently negate any differences in assigned specified rep durations at the beginning of each set/exercise. Perhaps researchers should designate the set end-point (e.g., muscular failure) as the inability to maintain the assigned rep duration for concentric and eccentric muscle actions throughout the set while maintaining proper exercise form.
And let’s just say that this idea has huge problems. The primary one here is that as fatigue sets in and a trainee approaches form failure, repetition speed invariably slows down.
While I have no intention of getting into the weeds, just a ton of data has examined the relationship between either intensity (as a percentage of 1RM) or training to failure in terms of how velocity changes. And what the overall picture shows is that:
- As a trainee approaches muscular failure, repetition speed slows
- The higher the relative intensity, the slower the repetition
So the first 10 reps of a 15 rep set might move pretty quickly before starting to slow, slow more, slooow mooorre and sloooooowwwwwww mooooorrrreeee. Similarly, 75% of 1RM will move faster than 85% which will be faster than 90% or 100%.
Basically, the closer to maximal force output a muscle is, the slower the movement speed will be.
And that’s the problem with using repetition speed as a criteria: even if a trainee attempts to move the bar with maximal (or some submaximal velocity), the speed of movement will slow as muscular failure is approached and eventually reached.
As I’ll show in the final part of this series, often it slows significantly. If a set is stopped when the lifter is moving more slowly than the goal repetition speed, that set will by definition, not be to physiological muscular task failure. Rather it will be several repetitions away from it.
To that I’d add the corollary: if the bar speed never slows during a set, the set wasn’t to physiological muscular failure. It might not have even been close.
Defining Muscular Failure
Ok, I’ve addressed enough individual definitions. Let’s put them all together and come up with a meaningful definition of what muscular failure actually represents in the weight room.
In its most general form, muscular failure or momentary muscular failure or volitional failure as you sometimes see it called should actually represent the inability to generate sufficient force to match or exceed the force requirements of the movement.
Because even ignoring the issue of form failure, the technical requirement of the movement and the trainee’s technical ability, any definition of actual muscular failure should be essentially:
An inability to perform another repetition despite a maximal effort being given.
With the bolded bit being the key here. Muscular failure does not occur when a trainee decides they have had enough, or get uncomfortable or decide by their own volition to quit. It occurs when they can no longer perform another repetition despite giving an all out muscular effort.
To that we might add that true failure cannot be said to have occurred until the trainee actually attempts the next repetition. Because outside of some specific situations, that you’ll see in the final part, you don’t know that you’ve failed (or hit an RM) until you fail (or only completed the previous repetition.
As Steele et al. phrase it:
Involuntary set point is the key here and goes back to the idea of volitional fatigue. Going to true muscular failure means a true physiological inability to complete another repetition no matter how much effort you provide. Thus the end point is involuntary in the sense that you had no control over your inability to complete the repetition. You couldn’t physiologically have generated more force.
Back to Form Failure
Yes, fine, there is the form issue and you can add “using proper technique” to this. But that brings up all the issues I raised in the previous part. The simply reality is that the average trainee can’t or won’t apply the definition I gave above in most complex exercises. Form will break first. Which has all those implications I brought up for training practice and research last time.
The issue being this: your muscles don’t give a damn physiologically when your form breaks. If your quads are the target muscle and your form breaks 5 reps before they are approaching true physiological muscular failure, it doesn’t matter.
Well it does in that it means that your set of squats “to failure” weren’t a very good quad stimulus movement. Because the form aspect of failure prevented the set from taking your quads anywhere near physiological muscular failure.
There is No Form Failure on Machines
But I’d note that many of the writers offering the above definitions come from a distinctly HIT background. Steele, Fisher, Carpinelli have all been towards that end of the science. On a leg press or chest press there is no real form failure to occur. T
rue muscular failure here does not occur until the lifter is unable to complete another full range repetition (i.e. get through the sticking point) despite giving maximal muscular effort.
Again the bolded bit is the key here. Because in a purely physiological sense of your muscles and what they experience or what constitutes a training stimulus, that’s all that matters.
But even in this case, you will find most people simply giving up (volitional failure) because it’s hard or uncomfortable rather than hitting true muscular failure. Even using a common definition of muscular failure in research still presumes that the trainees can get there. That’s certainly harder to control but is an issue to consider.
Why Definitions Matter
And this ties back in to my comments in the first part of this series as to why these definitions matter. If you are comparing different volumes of training and the nature of the training setup is such that the trainee’s form is breaking or they are giving up before physiological muscular failure, then you are not measuring what you think you are measuring.
A set of 10 that the subject just stops on because it’s hard when they could have done 15 is not physiologically the same as a set of 10 where they gave a maximum effort. And in the effective reps framework, the implications would seem obvious. The first set might give 1 effective rep if that, the second 3-5.
And suddenly your low volume group where people quit on squats only generated 1 effective rep per workout while the high volume group generated 5 (5 sets of 1 effective rep per set). And sure you did leg press and leg extensions “to failure” which added a few more to be sure. Though I still want to see the videos of these workouts.
But now what you’re really comparing is a totally suboptimal volume in the low volume group to what might be approaching a decent volume in the higher volume groups. And suddenly it looks like you need 45 sets/week to get the most growth because it’s really the equivalent of 1/3rd as many truly hard sets where people reached actual muscular failure rather than having their form break or giving up because your workout design had too short of a rest interval.
Or consider the Haun et al. study Mike Israetel was involved with. It worked up to 32 sets/week of squats with sets of 10 at 4 RIR with a 10′ break. That’s maybe 1 effective rep per set or 32 effective reps per week. The same number that perhaps 8 sets to true muscular failure would have achieved (assuming 4 effective reps per set).
And then you try to compare those studies to other studies using different definitions of failure and you’re comparing apples and oranges.
Failure is At Least Consistent
When I talked about training volume, I pointed out that using sets, reps and volume load all have severe limitations in terms of their use. In contrast, assuming that the same definition is used, counting sets to failure may provide a much better approach.
Related: What is Training Volume?
Because with some range of loading parameters (perhaps 6-20+ reps), it appears that 3 sets to failure is equivalent to 3 sets of failure, almost irrespective of anything else. Reps don’t matter much, volume load certainly doesn’t matter. Sets to failure seems to be what matters.
Once again, this fits well within the “effective reps” framework as 3 sets of 8 to failure and 3 sets of 30 to failure will be generating roughly the same number of effective reps per set.
But this is only the case if a consistent definition of failure is being used. Which clearly isn’t always the case.
Because 3 sets of 8 to true physiological muscular failure in the leg press, where form failure should be damn close to physiological muscular failure, can’t be equivalent to 3 sets of 8 in the squat to “form failure” where failure occurs due to poor technical skill or the trainee giving up because it’s too hard.
Because what you’d expect to see is that the study or workout where the definition of failure caused the sets to be terminated before true physiological muscular failure will “need” more sets to achieve optimum gains compared to studies that don’t.
And when I finally get around to updating my training volume and hypertrophy series, I’ll look at the research within this framework. And I think a lot of the discrepancies and “controversy” between studies will disappear.
Related: How Much Volume Should I Do to Grow?
I mean not that there’s any real controversy anymore as basically the entire group that fought with me for 18 months has walked it back to agree with what I said all along. Even if none of them have the sack to actually come out and say “Lyle was right all along.” But that’s par for the course in this industry.
Which is as good a place to wrap this up as any. In the next (and I promise final) part, I’ll wrap up by looking at where RIR/RTF fit into this, make some more rambling and repetitive commentary before putting up some videos to demonstrate what this looks like in practice.
- What is Training Intensity?
- What is Muscular Failure: The Weight Room Part 2
- What is Muscular Failure: The Weight Room Part 4
- What is the Optimal Rest Interval Between Sets?
- What is Muscular Failure: Definitions